Power amplifier protection circuit
US4417292A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 13, 1982 |
| Grant date | Nov 22, 1983 |
| Priority date | — |
| Expiry date | May 13, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K4/693
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A protective current mirror, with a reflection ratio greater than one, is connected as the active load of an input differential amplifier of a power amplifier. This mirror is provided in addition to the usual current mirror which has its output connected to the drive transistor of the output power amplifier stage. The protective mirror senses the imbalance due to a voltage peak which occurs at an inverted input of the input differential amplifier at the very beginning of the descending portion of a sawtooth input signal ramp voltage and the protective mirror operates a protective transistor which is connected to the base of the power amplifier drive transistor so as to keep one power transistor of the final power amplifier stage in its inactive state. Protection of the output power transistor occurs before the output of the power amplifier has reached its maximum voltage level.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.